A typical electrical connector includes some form of dielectric housing for mating with a complementary connecting device, such as a mating connector. The housing may be adapted for mounting on a printed circuit board, with a receptacle for mating with the complementary connector, or the housing may receive a second printed circuit board in a board-to-board connection. Whatever the connector configuration, the dielectric housing typically mounts a plurality of conductive terminals or contacts.
An electrical terminal normally includes a terminating portion or end and a contact portion or end. The terminating end is terminated to an electrical wire, a circuit trace on a printed circuit board, a conductor strip on a flat flexible cable or any other conductor of an appropriate electrical device. The contact end of the terminal is adapted for engaging a contact or a contact portion of a terminal of the electrical device to which the connector is mated or interfaced, such as the complementary mating connector. It is frequently desirable to plate the contact portion or end of the terminal with a highly conductive material, such as a precious metal like gold. For obvious cost considerations, the entire terminal preferably is not plated but only the contact portion. In addition, the body or thickness of the terminal is not fabricated of such highly conductive materials as gold, because of the cost and such materials do not provide the resiliency necessary for most terminals. It should be understood, however, the invention herein is not limited to electrical terminals and is equally applicable and advantageous for fabricating a variety of electrical components whether the base material is conductive or non-conductive.
With that understanding, contact portions of some electrical terminals are easily plated with plating material when the contact portions of the terminals are at extreme or distal ends of the terminal configurations. Those ends simply are dipped or immersed in an electrolytic bath to cover the end contact portions and the plating material is electro-plated on those ends. Still with this method, plating material is plated on unnecessary portions of the terminals such as portions that do not contact the mating terminal. Moreover, in many applications, the contact portions of the terminals are not at ends or edges thereof, and the dipping process cannot be used. In those applications, a mechanical masking device is applied to the terminals to screen areas not to be plated, leaving the contact portions of the terminals exposed. The terminals then are immersed in an electro-plating bath, and only the contact portions of the terminals become plated. Problems continue to occur in designing systems or processes for applying mask materials to such electrical components, particularly when the components are three-dimensional. For instance, an ink-jet type process or applicator has been used for applying the mask material, but such processes have been limited primarily to applications where the mask material is applied to one side of a substrate, sheet or film which has a portion or spot to be plated. Such processes have not been used for applying mask materials to a plurality of sides of a multi-sided electrical component. The present invention is directed to solving these problems and providing a process for applying the printing material to three-dimensional electrical components, such as electrical terminals.